Chilled product dispensing apparatus

ABSTRACT

An apparatus for refrigerating and dispensing soft serve food products from one or more containers of product maintained at temperatures, respectively, appropriate for the products. The containers comprise flexible and impermeable bags having heat sink structures contained therein and the apparatus includes respective container receptacles and a refrigeration system having cooling sections located adjacent the respective receptacles wherein the cooling sections are aligned with the heat sink structures of the containers when the containers are seated within the receptacles. Adjustable refrigerant controls are provided for controlling the flow of refrigerant to the respective cooling sections and a monitoring system, including pneumatic and electric control circuits, provides signals corresponding to the volume of space in a container receptacle external of the flexible bag to detect the existence of an empty or nearly empty container. The monitoring system includes a comparison and logic circuit as well as signal generators for indicating that a product container is empty. The refrigerant system is also operable in a defrosting mode for raising the temperatures of the products in the respective containers and for deicing the containers and receptacles.

FIELD OF THE INVENTION

This invention relates to chilled product dispensing apparatus and, moreparticularly, to apparatus for dispensing chilled or soft frozen foodproducts such as ice creams, frozen yogurts, custards, and the like.

BACKGROUND OF THE INVENTION

Apparatus for dispensing soft frozen food products are of commercialinterest for installations in retail establishments, wherein they areoperated by customers or employees for dispensing soft frozen productsinto individual containers such as serving dishes or edible cones. Softserve products, i.e., chilled or soft frozen products, are maintainedwithin such a dispensing apparatus at a temperature which is not so lowas to prevent the extrusion of a continuous stream or ribbon of themixture, yet not so high that the extruded product is sufficiently fluidthat it does not retain its shape for a period of time in the container.

It is thus important that such a soft serve product is maintained withina temperature range which is appropriate for dispensing the particularproduct. Typically, this may constitute a range of only several degrees,falling between about 0° F. to 20° F. for soft frozen confections suchas ice creams and yogurts, but the range may differ with respect todifferent types of products. For example, temperatures suitable for thedispensing of products with relatively high fat contents, such as icecreams, are lower than those appropriate for low-fat products, such asdietetic yogurts and the like. Excessively low temperatures often havedeleterious effects upon the taste and consistency of the product, whichmay crystallize and become undesirably hard and which may not flowconsistently during operation of the dispensing apparatus. Thetemperatures at which such soft frozen confections are maintained fordispensing the products are thus rather critical, and they are somewhathigher than those preferred for storing the products.

BACKGROUND OF THE PRIOR ART

Refrigerated soft serve mixing and processing apparatus of a first typehave been developed which are operable to process and freeze theproducts on-site, suitably at retail establishments in which theproducts are to be sold to the public. In such apparatus a liquid mix istypically converted into a soft frozen confection by lowering thetemperature of the mix within a refrigerated vat while stirring the mixwith an agitator or dasher. However, such on-site production of softserve products entails a number of disadvantages and difficulties.First, processing the liquid mix and bringing it to a desiredsubfreezing temperature is inconvenient and time consuming. Also, thedasher assembly and other movable components in such an apparatus mustbe periodically cleaned and serviced, and the mechanical drive mechanismrequired for operating the dasher includes a number of moving partswhich may be subject to malfunctions. The liquid mixtures utilized insuch apparatus are more susceptible to bacterial contamination than isthe case with products which are consistently maintained in a frozenstate, and, accordingly, cleaning and disinfecting of the componentsmust be performed frequently if bacterial contamination is to beavoided. Further, since such on-site processing systems typically areoperated by various employees of local retail establishments, it isdifficult to maintain consistent quality control, and the resultantproduct may be inferior in taste and consistency to one which isprocessed in a central location, under carefully controlled conditions,and shipped to the retail establishment in frozen form. For example, theprocess of air entrapment within the mix by the rotating dasher as themix is cooled to a freezing temperature is difficult to performconsistently in such on-site processing apparatus, often resulting inthe product having insufficient air entrapment. Thus, the product maynot have the desired consistency, and the yield is reduced, which mayaffect the ongoing costs and profitability of the installation.

Accordingly, a second type of soft frozen product dispensing apparatushas been devised in which the product is shipped in suitable containersin pre-processed, hard frozen form, suitably at sub-zero temperatures,and "tempered", or brought to somewhat higher, serving temperatureranges (e.g., 10° F. to 20° F.) within the dispensing apparatus. In suchsystems, the mixture normally is shipped within containers which areadapted to be removably inserted within a refrigerated cabinet, andmeans have been provided for dispensing the mixture through one or moredispensing nozzles formed in a panel or door of the cabinet. In suchpre-processed soft serve dispensing apparatus, the product is thusprepared and processed in a central facility, and a high degree ofquality control may thereby be maintained. Moreover, such dispensingapparatus are conveniently operated as self service units, wherein acustomer may dispense the product into a serving container by actuatinga valve on the apparatus.

However, such pre-processed soft serve dispensing apparatus also haveentailed a number of disadvantages and limitations. For example, it ishighly desirable from a marketing standpoint that a variety of softserve products be made available to potential customers. However, aspreviously mentioned, temperatures appropriate for dispensing certaintypes of confections are not suitable for confections of other types.Accordingly, when it has been desired to dispense a variety of productshaving differing characteristics, it has not been conveniently possibleto maintain such products at respectively appropriate temperatureswithin a single dispensing unit.

One means for serving different types of soft serve products is toprovide multiple dispensing units, each with an independently controlledrefrigeration system for maintaining each product within its appropriatetemperature range. Or, a single unit can be employed in which severalsoft frozen products are maintained at a single temperature whichrepresents a compromise for one or more of the products, albeitresulting in the previously mentioned deleterious effects upon the tasteand consistency of the product. The first alternative is undesirablyexpensive, entailing the initial costs of multiple refrigerated unitsand substantial continuing expenses related to power consumption andmaintenance. Moreover, such multiple refrigerated units would require anexcessive amount of floor space, which is also competitivelydisadvantageous, particularly for small business establishments. Thesecond alternative is clearly undesirable from the standpoints ofproduct quality and customer satisfaction. Accordingly, there is a needfor a soft frozen food product dispensing apparatus in which containersof soft frozen products of differing types may be convenientlymaintained at selected temperatures appropriate for each type of softserve product.

A further disadvantage of existing systems of the type adapted todispense previously processed frozen products is that the entireinterior volume of the cabinet or housing in which containers of softfrozen product are housed is required to be maintained underrefrigeration, within a desired temperature range. The necessity formaintaining a consistent, precisely controlled temperature throughoutthe cabinet presents technical difficulties, and the costs of electricalpower for continuously refrigerating the entire cabinet at subfreezingtemperatures are substantial. Further, the generally cylindricalcontainers of pre-processed frozen confections may tend to becomeadhered to chilled receptacles or other components within the dispensingunit, because of the freezing of condensation which may form between thecontainers and adjacent components, whereby the containers tend tobecome adhered to components within the refrigerated units and aredifficult to remove. There is thus a need for a soft frozen productdispensing apparatus in which chilled receptacles for receivingcontainers of soft serve product may be quickly and convenientlydefrosted to permit release and replacement of the containers andcleaning or servicing of the apparatus.

A further limitation inherent in such existing soft serve dispensingapparatus relates to the difficulty of ensuring that the soft frozenproduct in a respective container is substantially exhausted prior toreplacement of the container, and the related difficulty of monitoringthe quantity of product remaining in each container to ensure that emptyor "nearly empty" containers are identified and replaced in a timely andsystematic manner. With respect to customer satisfaction andvolume-of-sales considerations, it is thus preferable that empty ornearly empty containers are replaced by an operator or service personprior to receiving customer complaints regarding an empty, andsupposedly inoperative, machine. However, it would be inconvenient, andwasteful of the product, to require the operator to monitor thedispensing units by repeatedly opening the nozzles and releasingquantities of the mixtures from time-to-time throughout the hours ofservice in order to detect the existence of an empty container. Thus,there is a need for an effective product monitoring system for detectingthe existence of an empty or nearly empty container and providing aclearly observable or audible indication thereof, permitting replacementof the container prior to receiving customer complaints regarding suchan empty container.

The containers of pre-processed soft frozen food products are typicallyof cylindrical configuration having a tubular housing and a flexible,impervious liner or bag extending within the tubular housing. Theflexible bag typically has a closed end and an opposite, open endcommunicating through an outlet conduit and dispensing valve within thedispensing apparatus, and subsequently with a dispensing nozzle.

With respect to mechanisms used in prior-art apparatus for effectingextrusion of the product from such containers, in some conventionalsystems, the product has been dispensed by means of a piston memberadapted to urge the liner and its contents toward the outlet. Suchpiston members, for example, have been actuated by expandable bellowsmechanisms. In a typical application, a force is thereby applied againstthe closed end of the flexible liner sufficient to cause the liner to betranslated inwardly within the rigid, tubular housing, urging theflexible liner and its contents toward the outlet. However, as the lineris pushed inwardly within the tubular housing, multiple pockets of theconfection are formed within the liner as it becomes compressed andfolded upon itself, and a substantial quantity of the mixture remainstrapped within the folds and pockets formed in the compressed liner. Itis obviously desirable that such waste of the soft frozen product beminimized, and there is thus a need for a soft serve dispensingapparatus in which substantially all of the product within suchcontainers is exhausted from the respective containers. As will be morefully described hereinbelow, in accordance with a preferred embodimentas described in co-pending application Ser. No. 07/856,623 filed Mar.24, 1992 and assigned to the assignee of the present application,extrusion of the mixture from such a container is effected by applying agas under pressure to the container, externally of the flexible liner,whereby pressure is applied evenly over the external surface of theliner for exhausting substantially all of the product. Additionally, thecontainers heat sink structure contained within the flexible liner forpreventing the occurrence of locally heated regions within thecontainer, and adjacent its outlet, which would tend to result in aninconsistent, partially liquid product. As will become apparent from thedescription to follow, whereas this system entails a number ofadvantages over ordinary, piston-actuated extrusion mechanisms employedin conventional dispensing apparatus, precise determination of thequantity of mixture remaining in the container is difficult because ofthe distortion and irregularity of the flexible liner as it iscompressed within the tubular housing and within the heat sinkstructure.

With respect to the need for monitoring such systems in order to permittimely replacement of empty containers, precise measurement of thevolume of soft serve product remaining in such flexible liners isdifficult, partially because of the distortion of the flexiblecontainers during extrusion of the product. Additionally, in suchsystems there exists no linearly translatable piston member or the like,the displacement of which could permit a relatively convenient estimateof the degree of exhaustion of the product by means of conventionallinear displacement transducers or the like. Accordingly, there is afurther need for a reliable monitoring system capable of providing anindication of an empty or "nearly empty" container in such soft frozenproduct dispensing apparatus.

In conventional, soft frozen product dispensing apparatus, dispensing ofthe soft frozen product is controlled by various types of valvingmechanisms. Some systems have employed manually operated, proportionallyactuable valves, wherein a customer may adjust the valve by a desireddegree, generally by shifting a handle operably connected to a valveelement. However, such manually actuated dispensing systems entailcertain disadvantages, particularly when the soft serve dispensingapparatus is to be used in a self-service mode wherein customers usingthe machine may not be familiar with its operation or with the fluidcharacteristics of the mixture as it is extruded. For example, acustomer may have difficulty in controlling such a proportionallyactuable valve to achieve a desired rate of flow of the mixture.Further, the customer, through negligence or because of a lack offamiliarity with the apparatus, may spill the product and may notpromptly close the valve to shut off the flow, resulting in unnecessaryloss of product. Such product loss is, of course, of major concern withrespect to profitability and with respect to the commercial viability ofsuch apparatus for customer operated installations. There is thus a needfor a soft serve dispensing apparatus having an improved valving andshutoff system for controlling the extrusion of soft serve confections,wherein the dispensing valve is normally closed, and is automaticallyreturned to a closed position after use unless purposefully maintainedin an open position by an operator, and wherein gas under respectivelyappropriate pressure levels is applied for actuating the dispensingvalves and for ejecting the soft serve product.

OBJECTS OF THE INVENTION

It is, accordingly, a major object of the present invention to provide anew and improved apparatus for refrigerating and dispensing soft servefood products.

Another object of the invention is to provide such a soft serve productdispensing apparatus which is conveniently operable in a self-servicemode.

A further object is to provide such a soft serve product dispensingapparatus in which various types of soft serve products may bemaintained at differing temperatures appropriate for the respectiveproducts.

Another major object is to provide such a soft serve product dispensingapparatus which is particularly adapted to chill and dispense soft serveproducts in containers of the type having an elongated flexible bag orliner containing the product, and an elongated heat sink structure, theproduct dispensing apparatus having cooling sections respectivelylocated adjacent each container, in alignment with the respective heatsink structure of each container, for effectively removing heat from thesoft serve product by cooling the respective heat sink structures.

Yet another object is to provide such a soft serve product dispensingapparatus having a cabinet or housing in which containers of soft serveproduct are maintained within respective, precisely controlledtemperature ranges, but wherein it is not necessary to refrigerate theentire interior volume of the housing or cabinet.

A further object is to provide such a soft serve product dispensingapparatus which includes refrigerated receptacles or barrels forreceiving respective containers of pre-processed frozen products and asystem for quickly and conveniently defrosting the receptacles forfacilitating replacement of the containers and servicing of theapparatus.

Yet another object is to provide such a soft serve product dispensingapparatus which includes an effective monitoring system for detectingthe existence of an empty or nearly empty container of the soft frozenproduct, and which includes means providing an indication to an operatorof the existence of an empty or nearly empty container, therebypermitting replacement of such containers in a timely manner.

A related object is to provide such a self-service, soft servedispensing apparatus which includes a product dispensing valve which isnormally closed and which may be conveniently opened by a switchactuated by a customer, and wherein the dispensing valve returns to aclosed position upon release by the customer of the product dispensingswitch.

A further, related object is to provide such a valve actuating systemwhich includes means for damping the operation of the valve actuatingmechanism during opening and closing of the valve to minimize physicalshock and noise during operation of the product dispensing system.

Further objects and advantages of the invention will become apparentfrom the specification and accompanying claims and from the accompanyingdrawing.

SUMMARY OF THE INVENTION

In accordance with one preferred embodiment of the invention, a softserve product dispensing apparatus is provided which is adapted todispense pre-processed soft frozen food products of several types andconsistencies, maintaining containers of the respective soft serveproducts at differing temperatures appropriate for dispensing therespective soft serve products. A selectively controllable refrigerationsystem is provided in which a coolant is conducted through multiplesupply conduits to respective cooling units, which include receptaclesin which the respective containers of soft frozen products are removablyseated.

In accordance with another aspect of the invention, coolant is conductedto respective product container receptacles, and a defrosting system isprovided having selectively controllable communication between acompressor section and the container receptacles. The defrosting systemis operable for selectively conducting heated, pressurized coolantthrough cooling sections adjacent the respective receptacles for heatingand defrosting the receptacles, thereby facilitating removal andreplacement of respective containers of product seated within thereceptacles, and servicing of the apparatus.

In accordance with still another aspect of the invention, a pneumaticactuation system is provided for applying a pressure differential withinthe respective containers of soft frozen product which is effective tocause the product to flow in a steady stream through an outlet conduitand dispensing nozzle, a normally closed dispensing valve being providedfor controlling the flow of soft serve product through the dispensingnozzle. Electrical and pneumatic control systems are provided foreffecting opening of the valve in response to closing of a normally openactuating switch, and a control system is provided which ensures thatappropriate actuating pressures are maintained within a container of theproduct when the switch is actuated and for a predetermined timeinterval thereafter. In a preferred embodiment, means are provided fordamping movement of the valve element. In one preferred embodiment, thedamping system includes a pneumatic and hydraulic damping system.

In accordance with a further aspect of the invention, an electricallyand pneumatically controlled system is provided for introducing gasunder a first pressure from a first tank for effecting extrusion of asoft frozen product, and for supplying gas under a second, relativelyhigher pressure, contained in a second tank, for actuating a productdispensing valve to control the flow of a soft frozen product, andwherein a pneumatic control and valving system is provided for supplyinggas under pressure from a single source of gas under pressure, such asan air compressor, to the two tanks.

In accordance with yet another aspect of the invention, anelectronically and pneumatically controlled system is provided fordetecting the existence of an empty or nearly empty product containerand providing an indication of such a condition to permit timely andsystematic replacement of empty product containers. A control system andlogic circuit is provided for determining the existence of apredetermined interior volume of gas within a respective productcontainer which is indicative that the volume within the container, butexternal of the flexible liner, has become greater than a predeterminedvalue corresponding to a "product-empty" condition. The existence ofsuch an empty volume within a product container and external of theflexible liner is determined by a pneumatic and electronic system whichis operable to introduce gas under pressure within the respective foodproduct containers and then to permit release of the gas under pressurethrough a restrictive orifice, while sensing the time required for thepressure of the gas to fall by a predetermined increment as it isexhausted through the restrictive orifice, comparing the time delay witha predetermined reference delay period, and providing a "product empty"signal when the predetermined delay period is exceeded. In one preferredembodiment, the restrictive orifice is adjustable for permittingcalibration or adjustment of the system.

BRIEF DESCRIPTION OF DRAWINGS

For a more complete understanding of the invention, reference should bemade to the accompanying drawings, wherein:

FIG. 1 is a perspective view of the soft serve confection dispensingapparatus showing the dispensing head assemblies and controls;

FIG. 2 is a perspective, fragmentary view, in an enlarged scale, showingtwo of the product container cooling units, and wherein one of the headassemblies has been removed to reveal the corresponding productcontainer receptacle;

FIG. 3 is a longitudinal, sectional view of one of the product containerreceptacles showing one of the containers of soft serve product seatedtherein and also showing portions of the respective head assembly anddispensing valve, wherein the thicknesses of the container andreceptacle walls have been exaggerated for clarity, and showing indiagrammatic form portions of the pneumatic and hydraulic actuation anddamping systems;

FIG. 4 is an end view of the extrusion head of the heat sink dispensingtube;

FIG. 5 is a fragmentary, partially sectional view taken as on line V--Vof FIG. 4, showing the attachment mechanism for removably mounting thefirst head assembly on the cabinet, in sealing engagement with one ofthe chilled product receptacles;

FIG. 6 is a schematic diagram showing portions of the cooling system,the defrost system, and associated control elements;

FIG. 7 is a schematic and pictorial representation of the dispensingvalve actuator section;

FIG. 8 is a schematic representation showing electrical components ofthe refrigeration system, the defrost system, and the compressorprotection system;

FIG. 9 is a schematic representation of the pneumatic system and theproduct empty monitoring system;

FIG. 10 is a diagrammatic representation showing the logic circuitemployed in the product empty monitoring system;

FIG. 11 is a diagram showing the drop in pressure within a productcontainer receptacle over time under several conditions during operationof the product monitoring system; and

FIG. 12 is a diagrammatic representation of an alternative pressurerelief system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the description to follow, like parts are designated throughout thespecification and drawings with the same reference numerals,respectively. The drawings are not necessarily to scale, and in certainviews portions have been exaggerated for purposes of clarity.

With respect to the individual temperature controlled cooling barrels orreceptacles, the apparatus includes means for maintaining frozen foodmixtures within individual, removable containers at selectivelycontrolled temperatures within suitable temperature ranges. With respectto a frozen yogurt mixture, for example, a temperature range of 10-20degrees may be typical. Other products may require other temperatures,which may range from 0° F. to 50° F.

With initial reference to FIG. 1, the chilled or soft frozen foodproduct dispensing apparatus 10 of one preferred embodiment of theinvention suitably includes a cabinet 12 suitable of rectangularconfiguration having an upper front panel 14 which is connected tosidewalls 15, 16, and a lower front panel 18 on which product dispensinghead assemblies 20a, 20b, 20c, 20d are removably mounted.

In the preferred embodiment, and as will be more fully describedhereinbelow, product dispensing head assemblies 20a, 20b, 20c, 20d areremovably mounted on the front panel 18 adjacent respective openings 21(FIG. 2) formed in the lower panel 18, in sealing engagement with theouter ends of respective chilled, cylindrical product receptacles (FIG.3), which extend rearwardly within the cabinet 12 from front panel 18.Referring to FIG. 3, a first chilled product receptacle 22a, as typical,includes a cylindrical product barrel 24a, preferably of stainless steelor aluminum, having a forward end portion mounted within correspondingopening 21 formed through front panel section 18, and a rearward endportion sealingly mounted within an annular cover or cap member 26. Capmember 26 has a centrally formed opening 28 communicating with arearwardly extending, high pressure conduit 30, for reasons which willbecome apparent from the description to follow.

With continued reference to FIG. 3, soft serve product 32, which forillustrative purposes in the present description will be considered tobe a soft frozen dietetic yogurt confection having a preferred servingtemperature range of about 15° F. to 20° F., is contained within acylindrical product container 34a which is removably seated within thecylindrical, chilled product receptacle 22a. Product container 34aincludes an elongated, rigid, tubular housing member 36, adapted to seatwithin the cylindrical barrel 24a of chilled receptacle 22a, the tubularhousing member having an outer diameter slightly smaller than the innerdiameter of the chilled product receptacle barrel 24a for permittingsliding insertion of filled product containers within the barrel, andremoval of empty containers. The tubular member 36 is suitably formed ofa helically wound, rigid cardboard or paper material, or it may be ofother thin, stiff, lightweight materials. A flexible, elongated,impervious bag 38, suitably of 4 mil polyethylene material, extendsrearwardly within the tubular housing member 36 and has a forward, openend portion 40 which is folded over the forward end of tubular member36, and a rearward, closed end portion 42 which extends across thetubular member 36 adjacent the end cap 26 when the product container 34is filled with the soft serve product 32, as seen in FIG. 3. Duringtransport or storage prior to insertion within the chilled productreceptacle 22a, the open end portion 40 of product bag 38 is protectedby a removable cover, not shown, fitted over the forward end of tubularmember 36.

The head assembly 20a is suitably formed of a rigid plastic materialsuch as polypropylene or acrylic, and has a rearwardly open housingportion 44 of generally cup-shaped configuration adapted to fitsealingly over the barrel 24a, and the housing 44 having asemi-frustoconical lower wall portion 45 coaxial with a forwardlyprojecting, cylindrical extension portion 46 defining a dispensing port48. The housing 44 has a rearwardly projecting, peripheral annularflange portion 50 which is adapted to seat coaxially within the forwardend portion of the container tubular housing member 36, thereby fittingtightly within the folded over forward end portion 40 of the flexiblebag 38 for effecting sealing engagement between the bag 38 and anannular seal 52, which is press fitted within an outwardly flangedforward portion 53 of the receptacle barrel 24a and which encircles thetubular member 36. Because of the outwardly flanged end portion 53 ofbarrel 24, the resilient seal 52 is pressed securely into sealedrelation with the confronting surfaces of the barrel flange 53 andoverlapped portion 40 of bag 38 upon the head assembly 20a being urgedagainst the product container receptacle 22. Additionally, a secondO-ring seal 54 is seated within a corresponding annular groove formed inan annular, rear wall of housing 44, in register with the forward,portion 53 of cylindrical receptacle barrel 24a.

As disclosed in co-pending application Ser. No. 07/856,623, filed onMar. 24, 1992, the cylindrical product container 34a, in its preferredembodiment, also includes a heat sink dispensing tube structure 56contained within the bag 38. The heat sink structure 56 includes atubular barrel portion 58 extending rearwardly within the flexible bag38 from its forward portion 40, and extending coaxially of the productcontainer tubular member 36. A perforated extrusion head portion 60 ofthe heat sink structure 56 extends across the forward end of barrelportion 58. As seen more clearly in FIG. 4, the extrusion head portion60 includes a plurality of openings 62 through which the frozenconfection 32 may flow when the product is dispensed. An extrusion headprojection member 64 extends forwardly from the extrusion head 60 andcoaxially within the product dispensing port 48. The heat sinkdispensing tube structure 56 is constructed of a material having a highcoefficient of thermal conductivity, such as aluminum, and one of itspurposes is to create a thermal heat sink for ensuring that thetemperature of the soft serve product 32 remains substantiallyconsistent within the dispensing port 48. Without the heat sinkstructure 56 the soft serve product would be subject to localizedheating since the head assembly housing 44 is exposed to thenonrefrigerated environment external of the cabinet 12. As discussed inthe above-referenced, copending application, the heat sink dispensingtube structure 56 preferably extends within the receptacle barrel 24 fora distance equal to about 50 percent of the length of the barrel foreffective dissipation of heat within the product container and theoutlet port 48. Additionally, an insulating cone member 66 of generallyfrustoconical configuration is coaxially seated within the inwardlyprojecting flange portion 50 of the head assembly housing 44 andincludes a forwardly projecting cylindrical extension 68 extendingcoaxially within the dispensing port 48, the cylindrical extension 68being sealingly seated, by annular seal 69, within cylindrical portion70 of the dispensing head assembly 20a.

As will be understood more fully from the description hereinbelow, ahelical cooling coil 74a of high pressure tubing, suitably 3/4-inchcopper tubing, encircles the cylindrical barrel 24a of chilled productreceptacle 22a at a location adjacent the heat sink dispensing tube 56.As will be described hereinbelow with reference to FIG. 6, arefrigerant, such as freon 502, may be conducted through the coolingcoil 74a for cooling the receptacle 22 and its contents, whereby heat iswithdrawn from the cylindrical barrel 24a, the tubular member 36, theheat sink dispensing tube 56 and the soft frozen confection 32 withincontainer 34 and dispensing port 48, thus dissipating heat within these74a, 74b, 74c, 74d (FIG. 6) elements away from the product dispensingpathway. As will be more fully discussed hereinbelow with reference toFIG. 6, cooling coil 74a, and cooling coils 74b, 74c, 74d (FIG.>6)institute evaporator sections in which refrigerant is permitted toevaporate for cooling the respective product container receptacles 22.Thus, the soft serve product 32 is cooled by cooling coil 74a and isprevented from becoming heated, and softening, by the heat sinkdispensing tube structure 56. Additionally, the product containerreceptacle 22a is insulated by means of an insulating Jacket 76,suitably formed of a closed-cell foamed material, extending around thecylindrical barrel member 24a and the cooling coil 74a and extendingrearwardly around the cap member 26. Similarly, the front panel 18 ofthe cabinet 12 is insulated suitably including an internal layer 77 ofclosed cell insulating material sandwiched between front and rear metalsheets 78, 80.

A second function of the heat sink dispensing tube structure 56 is tosupport the flexible bag 38 to prevent premature collapse of the bag andto ensure that it collapses in upon itself over the rear edge of theheat sink dispensing tube upon pressure being applied to urge theflexible bag 38 forwardly within barrel portion 58.

As will be more fully described hereinbelow, in operation, the softserve confection 32 is urged forwardly and caused to flow through theopenings 62, within extrusion head 60, and subsequently through thecylindrical projection 68, the dispensing port 48, and productdispensing valve assembly 82. Pressure is applied over the externalsurface of the flexible bag 38 by the introduction of a gas underpressure within the interior volume 83 of chilled product receptacle 22,external of the bag 38, and differential pressure across the bag therebyeffects extrusion of the product 32 through dispensing nozzle 84, uponvalve assembly 82 being open.

Valve assembly 82 includes an elongated, cylindrical piston valve member86 slidably seated within a valve chamber 88 vertically formed throughhead assembly 20a. In its closed position as shown in FIG. 3, the valvemember 86 extends across the dispensing port 48, upper and lower O-ringseals 90, 92 being seated within respective annular grooves coaxiallyencircling the valve member 86 and located above and below thedispensing port 48, for preventing leakage of the soft serve product 32when the valve member is in its closed position. The upper end portionof valve member 86 is connected with the lower end of a piston rod 94,which extends upwardly within an actuator 96, and is connected to pistonmember 98, which is slidably seated within chamber 100 of the actuator96. The piston rod 94 is connected at its lower end portion to drawvalve coupling 102, which is connected to valve member 86 by means of aball member 104 seated within a socket 106 formed in the upper endportion of valve member 86, through a keyhole slot 108 which permitsconvenient disassembly and removal of the piston rod 94 from the pistonvalve member 86 for ease of cleaning and assembly.

With reference to FIG. 5, the dispensing head assembly 20a is removablymounted on the cabinet lower wall portion 18, in sealing engagement withthe outer end of the receptacle barrel 22a, by means of flanged nuts110a, 110b which are threadingly engaged with outwardly projecting bolts112a and 112b. Bolts 112a, 112b are suitably fixedly mounted within avertical bracket member 114 which is welded or otherwise rigidly affixedto one side of the cylindrical barrel 24a. A second bracket member, notshown, is welded to the opposite side of the barrel 22a for supportingbolts which are threadingly engaged by the third and fourth flanged nuts110c, 110d (FIG. 2). Upon the flanged nuts 110 being tightened againstthe head assembly housing 44, the annular seals 52, 54 (FIG. 3) arebrought into sealing contact with the flanged end portion 53 and thefolded over portion 40 of the bag 38 for effecting sealing engagementbetween the bag 38 and receptacle barrel 24a.

In normal operation, the containers 34 of pre-processed soft serveproduct are supplied in hard frozen form. During processing of themixture, normally in a central facility, the soft frozen product 32 ispoured into the flexible bag 38, and the open end of the bag istemporarily sealed in a removable cover while the product is hardfrozen. The frozen food product may then be shipped, and stored, untilsuch time as it is tempered and placed into the receptacle 22, whereinit is maintained at a higher temperature in a soft serve consistency forpermitting dispensing of the product through the dispensing nozzle 84.

REFRIGERATION SYSTEM

Whereas in prior systems having multiple nozzles and product containersit has been necessary to maintain differing soft serve mixtures at thesame temperature, in the apparatus 0 of the present invention, selectivecontrol of the temperatures of each of several containers of soft serveproduct is provided. With reference now to FIG. 6, in accordance withone preferred embodiment, individual control of the temperatures ofmultiple (four) respective food containers is provided by controllingthe flow of coolant to evaporator coils 74a, 74b, 74c, 74d of eachrefrigerated product dispensing unit 116a, 116b, 116c, 116d. A singlerefrigerant condensing unit 118 is provided having a compressor 120connected through conduit 121 with a condenser unit 122. A commerciallyavailable condensing unit 118 such as Model MSYL-0027, manufactured bythe Coplend Corporation is suitably employed for compressing andcondensing the refrigerant, whereby the refrigerant may be conductedunder high pressure, in liquid form, to the evaporator coils 74a, 74b,74c, 74d. By way of example, the condensing unit 118 includes acompressor 120 driven an electric motor, not shown, of one-quarter horsepower. The refrigerant, in high pressure gaseous form, is conductedalong connecting line 121 to the condenser unit 122, which condenses itto liquid form and transmits it through outlet line 124 and liquidcoolant supply line 126 to a manifold line 128 connected to first,second, third and fourth solenoid valves 130a, 130b, 130c, 130d. A drierunit 132, suitably drier unit DX 052 manufactured by the DanfossCorporation, is connected in series between outlet line 124 and supplyline 126 for removing any moisture from the refrigerant.

With respect to the first product cooling and dispensing unit 116a, astypical of units 116b, 116c, 116d, the solenoid valve 130a is actuatedby power supply 134, suitably a 24 volt AC source, within a controlcircuit 136, to be described. An adjustable thermostatic control unit178a is provided including an adjustable thermostat 140 operativelyconnected to a normally open switch connected in series with powersupply 134 and the coil 143a of solenoid valve 130a. The thermostat 140is adjustable by an operator for selecting a desired temperature for agiven product, to be refrigerated and dispensed by the respectiveproduct dispensing unit 116a.

The thermostatic temperature control unit 138 thus includes anadjustable thermostat 140 controlling a normally open electrical switch178a connected in series with power source 134, and solenoid valve 130a.As shown in FIG. 3, the thermostat sensor 140' is preferably mountedinternally of the insulation Jacket 74 adjacent the stainless steelbarrel 24 for sensing the temperature of the barrel 24 and the adjacentproduct 32. The thermostat 140 is selected for the temperature rangedesired, and in the present embodiment a thermostat such as Model No.2E740 manufactured by The Dayton Corporation and having a range of -30°F. to 70° F., is suitably employed. The thermostatic temperature controlunit 138 of FIG. 6 is shown by way of example, and similar,corresponding units are provided for actuating the solenoids 130b, 130c,130d of each of the cooling coils 74a, 74b, 74c. A thermocouple 144 issimilarly mounted within the insulation Jacket 76 adjacent receptaclebarrel 24 (FIG. 3), and is connected by lead 146 (FIG. 6) to an externaldigital thermometer 148, which, as seen in FIG. 1, is suitably mountedon the cabinet front panel 14 adjacent the respective head assembly 20a.Similar thermometers and thermocouples are provided for the otherproduct dispensing units 116b, 116c, 116d. With continued primaryreference to FIG. 6, a conventional, thermostatic expansion valve 130ais connected in series between the solenoid valve 150 and theevaporative cooling coil 74a for controlling the flow of refrigerantthrough supply line 152 to the coil 74a, supply line 152 suitably beingcontinuous with the coil 74a. The thermostatic expansion valve 150 isconnected by tubing 154 to a power bulb sensing element 156, as shownalso in FIG. 3, mounted on refrigerant return line 158. The orifice ofthe thermostatic expansion valve 150 is adjusted proportionally to thetemperature related signal received through tubing 154 for controllingthe refrigerant flow. Expansion valve 150 thus serves to maintain anefficient rate of evaporation and superheating of the refrigerant as itflows through the coil, and withdraws heat from the adjacent productreceptacle 22a (FIG. 3). Refrigerant thus flows through supply line 152in compressed liquid form and refrigerant exiting from the evaporatorcoil 74a returns in a vaporous state through return line 158, manifold128 and through the low pressure suction or return line 160 to thecondensing unit 118.

DEFROSTING AND TIME DELAY CONTROL SYSTEM

In accordance with another advantageous feature of the present system,and with continued primary reference to FIG. 6, a defrosting system 162is provided which employs heated refrigerant in a gaseous state, inwhich it has been compressed by compressor 120 but prior to being cooledby the condenser 122. After operation of the soft serve dispensingapparatus 10 for an extended period, defrosting of the receptacles 22a(FIG. 3), is occasionally necessary to free one of the productcontainers 34 which may have become adhered to the adjacent chilledproduct container receptacle 22 because of the formation of ice betweenthe respective barrel 24 and the container 34 due to condensation on thesurface of the cooled, subfreezing barrel 24 over time. The highpressure conduit 121 connected between the compressor 120 and thecondenser 122 conducts refrigerant in a gaseous state, which has beencompressed and heated by the compressor, to the condenser 122 forcooling and liquification. The defrosting system includes a shuntingconduit 163 connected between high pressure conduit 121, through asolenoid actuated defrost control valve 164, to a defrost manifold line172. Accordingly, heated, compressed refrigerant in gaseous formconducted from the compressor 120 through line 121 under pressures of,for example, 250 p.s.i., and at temperatures of between 100° and 140° ,is conducted through line 163 to defrost solenoid valve 164, which isactuated by a normally open time delay relay 179 (FIG. 8) havingnormally open switch contacts 180 connected in series with a powersupply 170 for controlling solenoid valve 164, which is normally closeduntil opened by the relay. The electrical circuitry of the defrostsupply is shown in FIG. 8. Defrost switch 168 is physically positionedon the exterior of the cabinet 12 (FIG. 1) for convenient actuation byan operator. Upon being actuated by the push button operated switch 168,time delay relay 179 is energized and closes normally open relay switchelements 180 (FIG. 8) to energize solenoid coil 166 to maintain thesolenoid valve 164 (FIG. 6) in an open condition for approximately threeminutes, permitting heated gases to be conducted from line 163 (FIG. 6)through manifold line 172, through respective unidirectional checkvalves 174a, 174b, 174c, 174d, to the supply lines 152 which arecontinuous with respective evaporator coils 74a, 74b, 74c and 74d ofproduct cooling and dispensing units 116a, 116b, 116c, 116d,respectively, for rapidly raising the temperatures within the evaporatorcoils and thereby raising the temperature of the product receptaclebarrels 24 (FIG. 3) to melt any ice which may have formed between thereceptacle barrels and the product containers 34, thereby freeing thecontainers 34 and permitting their removal. Typically, after the heatedfreon has been passed through the cooling coils 74 for about threeminutes, the temperatures of the product receptacle barrels 24 areapproximately 35°. In some instances, a subsequent three-minute cyclemay be required to free a heavily frozen container. Subsequent to thethree minute time delay, and normally, after the removal of the productcontainers 34, the solenoid valve 164 is again closed, and cooledrefrigerant from condenser 122 (FIG. 6) is again conducted through theevaporator coils 74a, 74b, 74c, 74d to quickly bring the temperatures ofthe product container receptacles down to a preferred range of, forexample, 15-20 degrees. The receptacles will thereby be cooled tooperative temperatures within about 15 to 25 minutes. Unidirectionalcheck valves 174a, 174b, 174c, 174d (FIG. 6) are provided to preventreverse flow of the cooled refrigerant from one of the cooling coils,e.g., coil 74a, to the other coils during the refrigerant cycle, which,during normal cooling operations, would interfere with the individualtemperature control effected by the respective coils.

In the preferred embodiment, means are provided for selectivelyadjusting the temperature within the respective product containerreceptacles 22 and for turning off the compressor 120 when all of therefrigerant supply solenoid valves 130a, 103b, 130c, 130d are closed,for preventing over pressurization of the refrigerant should thecompressor continue to pump the refrigerant against the closed solenoidvalves. Because of the multiple refrigerant supply circuits of thepresent system, an OR logic system is provided, as shown in FIG. 8, forsensing the closure of the respective solenoid valves 130a, 130b, 130c,130d (FIG. 6). Referring to FIG. 8, the electrical coils 143a, 143b,143c, 143d of solenoid valves 130a, 130b, 130c, 130d are connected inseries with outlet leads 176a, 176b, 176c and 176d, which are connectedto respective adjustable thermostat switches 178a, 178b, 178c, 178d,which are operable to close their respective switch elements to applypower to open solenoid valves 130a, 130b, 130c, 130d when thetemperatures within the product receptacles, as sensed by theirrespective sensor elements 140 (FIGS. 3, 6) rise above the temperatureset in the thermostats. Thus, when the thermostats 178a, 178b, 178c,178d are closed, they are operable to emit signals to energize and openthe respective solenoid valves 130a, 130b, 130c, 130d to effect coolingof the respective product container receptacles, thereby permittingadjustment, by adjusting variable thermostats 178a, 178b, 178c, 178b, ofthe temperature within each product container receptacle. Adjustment ofthe temperatures is accomplished by adjusting the thermostat settings,by rotating screws 179, as shown in FIG. 2, positioned adjacent therespective product dispensing heads.

Referring to FIG. 8, OR logic circuit, comprising relay 184, connectedin series with paralleled diodes 186a, 186b, 186c, 186d, connectedrespectively with lines 176a, 176b, 176c, 176d, is provided formaintaining relay 184 in an actuated state, should any one of the relayswitches 178a, 178b, 178c, 178d be closed wherein any one of thesolenoid valves 130a, 130b, 130c, 130d (FIG. 6) are open for conductingrefrigerant. When relay 184 is actuated, closing relay switch 186,actuating time delay relay 187, which closes switch element 190 whichenergizes power relay 191 which loses switch 167 to apply 115 V ACcurrent to the compressor 120. Time delay relay 187 provides a 15 minutedelay to prevent starting the compressor against an existing highpressure. Capacitor 188 is connected in parallel with relay coil 184 forsmoothing the DC voltage applied to relay coil 184. In the event all ofthe switches 178a, 178b, 178c, 178d are open, whereby all of thesolenoids 130a, 130b, 130c, 130d are closed, to prevent flow ofrefrigerant from the compressor 120 (FIG. 6), the relay 184 isdeactivated, whereby the normally open switch 186 is open, turning offthe compressor 120 to stop further compression of refrigerant. Duringthe defrost cycle, the normally open switch 193, which is another relayswitch element of relay 179 is closed to energize relay 191 to closeswitch 167, turning on the compressor 120.

PRODUCT DISPENSING AND PRESSURE REGULATING SYSTEM

Referring to FIGS. 3 and 9, extrusion of the soft serve product 32 iseffected by means of a pneumatically actuated system 200 which isoperable to supply gas under pressure at, for example, 40 p.s.i., from asupply of air under pressure, to be described, through line 30a (FIG. 3)and liners 30b, 30c, 30d to the chambers defined within the productreceptacles 22a, 22b, 22c, 22d, for urging the soft serve product 32forwardly and outwardly through the dispensing nozzles.

Referring additionally to FIG. 7, the pneumatic system is also operablefor actuating the dispensing valve opening and closing mechanisms. Withrespect to the actuating system associated with the product dispensingvalve 82 of the first product dispensing unit 116a, a normally openproduct dispensing switch 202 is actuated by push button 204 which isconveniently located on the cabinet front panel 14, as seen in FIG. 1,adjacent the first head assembly 20a. In use, product dispensing switch202 is depressed by a customer wishing to dispense a quantity of thesoft serve product contained within the respective, adjacent productdispensing unit. As will be more fully described, in operation, so longas the push button 204 is depressed to maintain switch 202 in a closedposition, the product 32 continues to flow through the outlet nozzle 84,as will now be described with primary reference to FIG. 7. Productdispensing switch 202 is connected between a low voltage DC power supply242, and the coil 206 of normally closed solenoid valve 208, which isconnected in series between a high pressure source 210 of gas underpressure, to be described. In the present embodiment, the high pressuresource 210 is suitably a source of compressed air, of about 100 p.s.i.,as will be described with respect to FIG. 9. High pressure gas is thusconducted via conduit 207 through solenoid valve 208a to afluid-dampened actuating system 212 for opening the normally closedproduct dispensing valve 82. Fluid-dampened product dispensing valveactuating system 212 includes a fluid accumulator 214 partially filledwith a supply of a stable viscous liquid 216 such as glycerine, suitablyof 97 percent purity, within the reservoir 218. Accumulator 214 includesa restrictive outlet orifice 220, suitably of three to five millimetersin diameter, which is connected through conduit 222 to lower chamberportion 224 of dispensing valve actuator 96. The purpose of theaccumulator 214 is to dampen the application of actuating liquid toactuator 96, as will now be described.

When solenoid valve 208 is opened, in response to closing of productdispensing switch 202, high pressure gas is conducted via conduit 207,through solenoid valve 208 to the volume 226 within accumulatorreservoir 218 above the glycerine 216, and the resulting increase ofpressure within the reservoir 218 forces the glycerine outwardly throughrestrictive orifice 220 and conduit 222, whereby glycerine is introducedinto lower chamber portion 224 of the actuator 96 beneath piston member98 for urging the piston member upwardly. Upward movement of pistonmember 98 effects upward movement of piston rod 94. Piston rod 94includes an upper segment 94a and a lower segment 94b, the lower segmentbeing connected to coupling 102 which is connected to valve member 86 ofthe dispensing valve 82 (as also seen in greater detail in FIG. 3). Asthe valve element 86 is upwardly withdrawn from dispensing port 48, thesoft serve product 32 is permitted to flow through dispensing nozzle 84.The accumulator 214, with restrictive orifice 220, serve to damp theresponse of actuator 96 to application of high pressure air applied whensolenoid valve 208 is opened. Pressure is permitted to accumulate withinchamber 226, and the glycerine oil 216 flows through orifice 220 andconduit 222 in a dampened, gradually accelerating stream, whereby themovement of piston 98 and valve member 86 is correspondingly dampened.

In the preferred embodiment of the present invention, closing of theproduct dispensing switch 202 is also effective to effect theapplication of what will be termed "low pressure gas," which is suitablyair under pressure of about 40 p.s.i., to the empty volume 83 withinchilled product receptacle 22a (FIG. 3) for urging the flexible bag 38and its contents forwardly through the outlet port 48 and now openeddispensing nozzle 84, as will now be described. As may be seen mostclearly in FIG. 9, the upper section 94a of actuator piston rod 94includes a tapered upper end portion defining a bevelled surface whichis aligned with a microswitch element 230 operatively connected tonormally open microswitch 232. Microswitch 232 is connected byconductors 234a, 234b and 236, between conductors 238, 240, conductor238 being connected to a positive terminal of flow voltage (e.g., 24 VDC) power source 242, and conductor 240 being connected, when switch 202is closed, to ground. Conductors 234a, 234b are connected in series witha first, V₁ solenoid valve 244, the valve element of which is connectedby conduit 246 to the low pressure, 40 p.s.i. air source, to bedescribed, and conduit 30 which is connected in communication, throughopening 28 (FIG. 3) with the interior volume 83 within product containerreceptacle 22a (FIG. 3).

In operation, upon actuation of the dispensing valve 82 by closingproduct dispensing switch 202, as the upper segment 94a of piston shaft94, is translated upwardly, and the bevelled surface 228 is brought intocontact with microswitch element 230 for closing normally openelectrical switch 232 to apply electrical power through conductors 234a,234b to open normally closed (V₁) solenoid valve 244, which thencommunication between conduits 246, 30, permitting 40 p.s.i., lowpressure gas to flow into the inner volume 83 of the product containerreceptacle 22a (FIG. 3). Accordingly, the soft serve product 32 is urgedforwardly toward the outlet 48 and the dispensing nozzle 84 by pressureapplied evenly over the entire external surface of the flexible productbag 38. Accordingly, the bag 38 is compressed inwardly and is foldedinwardly within the heat sink dispensing tube structure 56 whereby thesoft serve product 32 is substantially completely exhausted.

In the preferred embodiment, the closing of microswitch 230 also effectsthe actuation of a time delay circuit system for maintaining "lowpressure gas" within the chamber 83 for a predetermined time period,e.g., for 30 minutes, as will now be described. Closing of microswitch232 is effective to connect power supply 242 to solenoid 248,operatively connected to normally open (V₂) valve V250 normally opensolenoid valve 250 is closed upon actuation by current conducted throughthe microswitch 232, in response to closing of the dispensing switch202, and the valve 250 remains closed for a period of time subsequent tothis operation, as will be described hereinbelow. As will be understoodfrom the description to follow, closing valve 250 (V₂) is effective tomaintain an appropriate pressure within product receptacle 22a duringapplication of low pressure gas, i.e., 40 p.s.i. to eject the product.The purpose of the time delay system is to maintain pressure within thereceptacle 22a for a preselected period of time and subsequently releaseand remove the pressure from the system, at a selected time afteroperation of the system. Thus, actuating pressure is maintained for aperiod of time after each use so that the product may be dispensedquickly by a subsequent customer, but operating pressure is releasedafter the selected time period to reduce strain upon elements of thesystem and to extend the life span of the system and also to preventdeterioration of the soft serve product 32 which may occur if it ismaintained under high pressures for an extended period of time.

With continued reference to FIG. 9, third solenoid actuated valve 208(V₃) has fluid communication through conduit 207 with the source of highpressure gas, and, through conduit 224, with the accumulator 214. Coil206 of solenoid valve 208 is connected through product dispensing switch202 with power supply 242. (normally open push button preferably beingmounted on the top or side of the cabinet for actuation by an operator.)An additional solenoid actuated relief valve 252 (FIG. 9) is suitablyprovided in connection with a common exhaust chamber 254 for permittingthe removal of low pressure gas within the system when it is desired toremove the head assemblies 20 for serving or, for replacement of emptyfood containers with full containers.

When the customer or operator has completed the dispensing of a desiredquantity of product from a selected one of the units 20a, he or shereleases the respective push button 204 for the product dispensingswitch 202, which is effective to release the associated solenoid valve,e.g., valve 208a, to prevent further supply of high pressure gas to theaccumulator 212. Solenoid valve 208a is a three-way valve having anoutlet 256, and when is closed, communication is provided betweenexhaust outlet opening 256 and conduit 209, whereupon pressure isreleased from chamber 218 above the glycerine fluid 216 withinaccumulator 214. The low pressure gas conducted through conduit 207 tothe upper piston chamber 225 within actuator 96a is then effective tourge the piston 98 downwardly, forcing the glycerine liquid 216 backinto the accumulator 214 and closing the product dispensing valve 82.With additional reference to FIG. 9, the pneumatic circuits of theapparatus are shown in schematic form, wherein the pneumatic system foractuating the dispensing valves 96 is shown generally at 260; whereinthe pneumatic system for regulating flow of low pressure gas to theproduct barrels for ejecting the soft serve product is shown generallyat 200, and wherein the dual pressure air supply system is shown at 264.

DUAL PRESSURE AIR SUPPLY SYSTEM

In the preferred embodiment, "high pressure" gas, for actuating theproduct dispensing valves 96, and "low pressure gas" for ejecting thesoft serve product and actuating other components of the system, isprovided by a dual pressure air supply system 264, as will now bedescribed. With continued reference to FIG. 9, an air compressor 26b issuitably driven by an electric motor 268 of 1/4 horse power thecompressor assembly suitably being of 100 p.s.i. capacity. As will beunderstood from the description to follow, the air compressor 266 isoperable to apply air under pressure to first "low pressure" tank oraccumulator 211 and to second, "high pressure" tank or accumulator 210for operating the pneumatic elements of the system. Air under pressureis conducted from the air compressor 266, through line 270 to normallyclosed three-way solenoid valve 272. Solenoid valve 272 is opened by theapplication of electrical current through its coil 274, and it isconnected through one-way check valve 276, through conduits 277 and 278to the first, low pressure accumulator 211, which is used foraccumulating air under pressure, at about 80-100 p.s.i. Air underpressure in line 278 is conducted through line 278 and through one waycheck valve 280 to high pressure accumulator 210. Air under pressurewithin line 277 is also conducted through line 282 to a pressure chamberof a normally closed pressure actuated switch 284 such as Model No.69MV6 manufactured by the Furnas Company. Pressure switch 284 includes anormally open switch 286 which is electrically connected throughconductors 288, 290 to the relay coil 274 of solenoid valve 272 and toelectrical motor 268 for conducting power from 115V source 283 to themotor 268 and coil 274, upon switch elements 286 being closed. Pressureresponsive switch 284 is operable to open switch elements 286 andthereby interrupt power to the compressor motor 268 upon pressure withinthe system rising above a desired high pressure level, e.g., 100 p.s.i.Upon the pressure subsequently falling below 75-80 p.s.i., the switch286 will be permitted to close once more, permitting current to flow tothe motor for supplying air under pressure once more through solenoidcontrolled valve 272. Pressure within the high pressure tank 210 is alsoincreased when the compressor 260 is in operation, until pressure withinthe section 264 is equalized. Such equalization occurs when pressurewithin the tank 210 reaches the upper limit of the compressor 266, whichin the present embodiment is about 100 p.s.i. Similarly, pressure withinthe low pressure accumulator 211 will also reach 100 p.s.i. upon thecompressor 266 continuing to run for a period of time. Three-waysolenoid valve 272 serves to release pressure from the system when anupper pressure level is reached. Valve 272 is normally closed, but uponcurrent flowing through conductors 288, 290 to the motor 268 it isenergized and open, whereupon air under pressure from the compressor 266flows through the solenoid valve 272 to check valve 276 and conduit 277.Upon pressure responsive switch 284 opening switch elements 286 becauseof excess pressure within line 277, power to the solenoid valve 272 isinterrupted and the valve is closed, and air under pressure within line270 is permitted to exhaust through the exhaust port 272.

Whereas both accumulators 210, 211 receive and store air compressed tohigh pressure levels form compressor 266 a pressure regulator 294 isprovided for reducing the pressure of air supplied through low pressuresupply line 207. Regulator 294 is suitably a pressure reducing regulatorsuch as that manufactured by the Watts Company, as Model No. R364-01C,and serves to reduce pressure received on line 279 to approximately 40p.s.i. for actuating the dispensing of soft-serve product, andsubsequently losing dispensing valves 82, as has been previouslydescribed. Thus, low line 207 is connected to the upper piston chamberportions of actuators 96a, 96b, 96c, 96d. High pressure line 207 isconducted through solenoid valves 208a, 208b, 208c, 208d to theglycerine accumulators 214 for actuating the dispensing valves. A secondhigh pressure line 296 is connected from the accumulator 211 to a highpressure gage 298. Low pressure gage 299 is connected to low pressuremanifold line 215. Gages 298 and 299 are suitably mounted on the cabinet12 for providing an indicating of the internal pressures. Whereas onlyone pneumatic circuit has been described, with respect to first productdispensing unit 116a, it will be understood that similar actuatorcircuits 116b, 116c, and 116d are also connected to the low and highpressure lines 209, 207 lines, for operation in a similar fashion.

With continued reference to FIG. 9, and in particular to the valving andcontrol section 200, solenoid valves 244 V₁ are shown connected inseries between the low pressure supply line 216 and through lines 30a,30b, 30c, and 30d, to the product receptacles 221, 22b, 22c, and 22d.The supply lines 30 are also connected to 30 minute timed valves which,as previously described, will exhaust pressure through exhaust outletsfrom the respective lines and from the receptacles 22.

PRODUCT MONITORING SYSTEM

A further novel system is provided for indicating when the productcontainers 34 are nearing an empty state. As previously stated, becausethe system does not employ moveable pistons or the like to displace thesoft serve product, conventional sensors for detecting displacement ofsuch pistons may not be used, and an electronic and pneumatic system hasbeen provided for detecting the residual volume 83 within the respectiveproduct containers and external of the respective flexible product bags38. Assuming manifold valve 244 is open, whereby air under 40 p.s.i. isbeing supplied to the product container receptacle 22a whereby theproduct container is therefore pressurized at 40 p.s.i. Pressure switch320 is operable to close a circuit when pressure within the line reachesa level of, for example, 35 p.s.i.

In summary, solenoid valve 250 is opened in response to pressure fallingbelow 35 p.s.i. in response to a signal received from pressure switch320. Air under pressure is permitted to flow through valve 350 andthrough the filter 334 and through a restrictive orifice 336 which isadjustable to control the resistance to flow. Upon pressure within theexhaust line falling below 30 p.s.i., the second pressure valve isclosed, emitting a signal to the logic circuit which then is alsooperable to close valve 250 to prevent further loss of pressure withinthe system.

As was described with reference to the operation of the productdispensing switch 202 for actuating solenoid valve 208a, opening valve208a to permit the flow of high pressure gas to accumulator 214 whicheffects opening of the dispensing valve and upward movement of pistonrod 94. Movement of the piston rod 94 effects closing of microswitch 230to complete the circuit (FIG. 7). As the product dispensing valve 82 isopened to dispense the soft serve product, the attached valve rod, bymeans of its beveled surface 228, closes mircoswitch 230 which closesthe circuit to energize solenoids 244 and 250. Referring now to FIG. 10,the logic circuit 301 for product monitoring systems 305 is shown.Normally opened microswitch 230, when closed, completes a circuit from asource of low voltage power, e.g., 24 volt DC, connected to terminal300. Microswitch 230 is thus connected in series between a source ofpotential and a first flip-flop circuit 302 which, in normal operation,remain ON to conduct power to the manifold valve 244 (V1) also seen inFIG. 9, as part of valve assembly 254. Upon valve 244 being opened, "lowpressure" air, under a pressure of about 40 p.s.i., is conducted throughconduit 30a to the interior of the product container receptacle 22a forpressurizing the interior of the receptacle to eject the soft serveproduct. Additionally, closing of product dispensing switch 202 (FIGS. 7and 10) causes current to be conducted to a second flip flop 304 and atime delay device 306 (T2). Upon receiving a signal from line 308 atterminal R, the second flip-flop 304 emits a signal Q which is conductedthrough line 310 to one side of an exclusive OR gate 312. Exclusive ORgate 312 is operable to emit a "high" signal to solenoid 248 V₂ uponreceiving an input from the second flip-flop 304 unless a signal is alsoreceived on its other input through lead 314, as occurs during operationof the product monitoring system, to be described. The second flip-flop304 is suitably purchased as an integral unit having a time delay relaywhich is operable to prevent the conduction therethrough of current fora desired delay period, suitably 30 minutes, following an ON conditionof the second flip-flop 304, whereby a positive output will be fed fromthe output of the second flip-flop through line 310. Time delay relay306 thus remains open for a 30-minute period following the actuation ofproduct dispensing switch 202. After the 30 minute period, relay 306becomes conductive, and a signal is conducted through line 314, timedelay relay 306, and line 316, to the S input of the second flip-flop304, which turns the second flip-flop OFF. Upon flip-flop 304 beingturned OFF, the signal is removed from the first terminal of exclusiveOR gate 312, turning it OFF and thereby deactivating valve 250, whichopens the valve and permits communication with the product containerreceptacle 22a (FIG. 9), relieving pressure within the receptacle 22a.

The electro-pneumatic circuit of FIG. 10 also provides a productmonitoring system, i.e., a system for testing the amount of soft serveproduct 32 remaining within the product container 34, as will now bedescribed. When testing for a "product empty" condition, upon themicroswitch 230 (FIG. 10) being closed, first flip-flop 302 is energizedto operate manifold valve 244, and pressure within the receptacle 22a israised to approximately 35 p.s.i. by the low pressure air. Upon thepressure reaching 35 p.s.i., a "35 p.s.i." pressure responsive switch320 is closed, whereupon the input to inverting NOR gate 322 is removed,and a potential is applied on line 324 to the R input of first flip-flopcircuit 302, turning it OFF, shutting manifold valves 244 and therebyremoving the source of low pressure air to the product containerreceptacle 22a. As low pressure switch 320 is closed, a potential isconducted on line 326 to one of the inputs of 0R gate 328, and OR gate328 is operable to emit a signal along lines 336 and 314 to the upperterminal of exclusive OR gate 312, which deenergizes the solenoid 248,opening valve 250 (FIG. 9). Upon valve 250 being opened, air underpressure within the receptacle 22a (FIG. 9) is permitted to exhaustthrough its outlet 28, and successively through valve 250, filter 334,and through an adjustable restrictive flow control orifice 336. Upon airunder pressure at 35 p.s.i. being conducted successively through valve250, conduit 338, filter 340, line 342, and restrictive orifice 336, asecond, "30 p.s.i." pressure responsive switch 344 is energized.Referring to FIG. 10, second pressure responsive switch 344 is energizedby air which is above its 30 p.s.i. threshold, closing pressure switch344 and conducting current along line 346 to the other terminal of ORgate 328, which is thereby caused to emit a signal to the upper terminalof exclusive OR gate 312, which then emits a signal to solenoid relay248 to close valve 250 (FIG. 9). Solenoid 248 is normally open, and uponreceiving a signal through exclusive OR gate 312 derived either from thesecond flip-flop 304 or the OR gate 328, it emits a signal whichmaintains solenoid 248 in an open condition.

Upon the air under pressure within product receptacle 22a beingexhausted through the flow control orifice 336 (FIG. 9), the pressurewithin conduit 242 communicating with pressure sensitive switch 344falls below 30 p.s.i., and pressure switch 344 is permitted to openagain, thereby removing the potential applied through lead 346 to ORgate 328 and removing the signal applied through lead 314 to theexclusive OR gate, thereby turning ON the solenoid 248, since exclusiveOR gate 312 will emit a signal when either of its inputs receives asignal. Therefore, valve 250 of solenoid 248 is closed, leaving a 30p.s.i. pressure within the receptacle 22a. A time delay relay 348 isconnected through lead 336, to the output terminal of OR gate 328, andthrough lead 350, with one input terminal of AND gate 352. Time delay348 is operable in response to signals received from the OR gate 328,which is turned ON if a signal is received from either pressure switch320 or switch 344 during the test. Thus, 35 p.s.i. switch 320 and timedelay relay 348 are turned ON when the test begins, i.e., when theproduct dispensing switch is closed. Switches 320 and 344 are bothturned on shortly after the product dispensing switch is closed. Shortlythereafter, 35 p.s.i. switch 320 is turned OFF as pressure within theline falls below 35 p.s.i. Within a short time period thereafter, e.g.,12 seconds, pressure within line 342 falls below 30 p.s.i. as air underpressure is exhausted through the restrictive orifice, and 30 p.s.i.switch 344 is turned OFF. At this time, OR gate 328 ceases to conduct,and a time delay relay 348 is triggered OFF. Thus, the relay 348, in thepresent embodiment, is operative to delay its output, i.e., to remainnon-conductive for a period of time of approximately 12 seconds, thereferenced time being selected as representative of that during whichthe pressure within the receptacle 22a falls from 35 to 30 p.s.i. whenthe associated product container is substantially empty of soft serveproduct. Thus, upon receiving an input from the OR gate 328, time delayrelay 348 remains non-conductive unless the signal duration is greaterthan 12 seconds. If that is the case, time delay relay 348 is closed,and a signal is conducted through lead 350 to AND gate 352. AND gate352, receiving the same signal on its other input terminal through lead354, is thereby switched to a conductive state, emitting a signal to athird flip-flop unit 356. AND gate 352 thereby switches flip-flop 356 toits "opposite" condition, turning ON output Q connected through lead 358to red indicator light 360, thereby illuminating the red indicatorlight. The red indicator light 360 is visible to an operator who maythen press the reset switch 362, whereby the third flip-flop 356 isagain reset, and a signal is emitted from Q through lead 364 toilluminate the green indicator light 366. At this point, the signalsupplied through switch 362 is also conducted through lead 368 and lead317 to the "S" input of the second flip-flop 304, turning flip-flop 304OFF, whereby the exclusive OR gate 312 is switched off, causing solenoid348 to open its valve 250 (FIG. 9) whereby the 30 p.s.i. pressure withinthe receptacle 22a is permitted to exhaust through the flow controlorifice 336. Air under pressure is thereby exhausted from the receptacle22a within about 30 seconds, whereupon it is safe for the operator tounscrew the head assembly 22a and replace the product container 34. Ifdesired, an additional pressure relief valve 368a (FIG. 9) operated by afurther pressure release switch, not shown, can be provided for quicklyrelieving pressure within the respective product container receptacle.In the preferred embodiment, one of the product empty monitoring systems305, as discussed above, is provided for each of the product containerreceptacles 22a, 22b, 22c, 22d, although only the system associated withthe first product container receptacle 22a has been described and shownin FIGS. 9 and 10, for simplifying the description and drawing. Uponreplacing the product container, it is preferable to maintain thedispensing switch 202 in a closed condition for several seconds untilpressure within the unit and within the new, full container of softserve product builds up and the product is caused to flow forwardlywithin its container, through the respective heat sink structure andwithin the front end of the receptacle 22a. The product dispensingswitch 202 applies a signal on line 308 to the R input of secondflip-flop 304, causing a Q output to be applied to the exclusive OR gate312, closing the valve 248, thereby permitting pressure once again tobuild up to 35 p.s.i. within the product container receptacle 22a.

Referring to FIG. 12, an alternative pressure relief system 370 is shownin association with product receptacles 22a, 22b, 22c, 22d and solenoidvalves 244 which control the flow of low pressure gas through lines 30a,30b, 30c, 30d to pressurize the receptacles 22a, 22b, 22c, 22d andsolenoid valves 244 which control the flow of low pressure gas throughlines 30a, 30b, 30c, 30d to pressurize the receptacles 22a, 22b, 22c,22d and extrude the soft serve product. In this alternative pressurerelief system 370, the product monitoring system 305 described abovewith reference to FIG. 9 is not used, and the pressure relief system ofFIG. 12 is employed instead. Referring to FIG. 7, the pressure reliefsystem 370 (FIG. 12) is actually 30 minutes after pressing of theproduct relief switch 205 by the customer or operator. Closing of switch205 actuates the dispensing valve actuator 96a, as previously described,closing microswitch 230, thereby closing the circuit to actuate the timememory delay relay 306 (FIGS. 7 and 12), closing valve 250, therebyretaining pressure within the respective product container receptacle22a (FIG. 12). After the timed delay, selected e.g., at 30 minutes, thetime delay device 306 automatically is deenergized, thereby deenergizingsolenoid coil 248, permitting valve 250 to open thereby releasing lowpressure air from the receptacle 22. Thus, the system 370 is effectiveautomatically to relieve pressure within the pneumatic system and thereceptacles if the apparatus 10 is not used for a period of time,preserving the system and preserving the consistency of the soft serveproduct contained therein.

The principle of the product tube empty indicator system is shown moreclearly in FIG. 11 wherein the slopes of curves 1, 2, and 3 representpressure versus time within the system following opening of valve 250with respect to a product container which is full (1), half full (2), orempty (3). Thus, a product container which is full of the product,having only a small amount of residual air volume, is quickly exhausted,and the pressure falls sharply as shown by line 1. A product containerwhich is half full has a substantially larger volume of air which takesa longer time to drop, as shown by line 2, and a product container whichis empty has a still larger volume of air which is exhausted over alonger period of time as shown by line 3. Thus, ΔT₁, ΔT₂ and ΔT₃ areindicative of the respective times, under each condition, for thepressure to drop from 35 p.s.i. to 30 p.s.i., AT3 being substantiallylonger than ΔT₁. The delta time is compared in the logic circuit with astandard time, provided by time delay relay 348, of, for example, 12seconds, and if the tested delta time is greater than 12 seconds, thelogic circuit indicates that the tube is empty and should be replaced.Suitably, the product empty warning device 360 is mounted on theexterior of the machine for indicating by red light or some otherindication that the tube is empty and should be replaced.

It will now be understood that the present invention provides a new andimproved apparatus for refrigerating and dispensing soft serve foodproducts and for providing selective, automatic control of thetemperatures within each of a plurality of containers of soft serveproducts, wherein soft serve products of differing types may bemaintained at temperatures appropriate for the respective productswithin a single food dispensing unit. Accordingly, soft serveconfections such as ice creams may be contained in one of the chilledreceptacles, and low fat products such as diet yogurt may be kept inanother. Moreover, the apparatus is particularly adapted forrefrigerating and dispensing soft serve products contained withinconveniently removable product containers of the type having a flexibleimpervious bag for containing the product and in which a heat sinkstructure is mounted within the container for preventing localizedheating of the product, and wherein the cooling sections, comprisingevaporative cooling coils, in the preferred embodiment, are positionedadjacent the chilled product container receptacles. In one preferredembodiment, they are positioned in alignment with the heat sinkstructures. Accordingly, the cooling coils are effective to remove heatfrom the respective, adjacent heat sink structures, thereby efficientlycooling the soft serve product contained therein upon refrigerant beingcirculated through and evaporated within the respective cooling coilsections. Further, the apparatus provides an efficient means for raisingthe temperatures within the respective product container receptaclesabove a freezing temperature for quickly and conveniently defrosting thereceptacles in the event one or more of the food product containersbecomes stuck within the respective receptacle because of the formationof ice due to condensation within the receptacle.

Additionally, the soft serve product dispensing apparatus of the presentinvention provides an effective system for detecting and indicating theexistence of an empty or nearly empty container of the soft serveproduct, the monitoring system being adapted to function efficiently inassociation with replaceable food product containers in which theproduct container bag is exhausted by means solely of differentialpressures, in which pressure within the product container receptacleexternal of the flexible bag is increased to effect extrusion of theproduct. The hydraulically and pneumatically operated dispensing valveis effective to permit convenient and reliable operation of thedispensing mechanism by a customer in a self-service installation, andoperation of the valving mechanism is effectively controlled by thedamping mechanism for enhancing reliability of the mechanism duringextended service. Additionally, the pneumatic valve return system,operated by low pressure gas applied to the upper surface of theactuator piston, is effective to consistently close the productdispensing valve mechanism for preventing waste of the soft serveproduct during use. The dual pressure air supply system is effective toprovide compressed gas under several pressure levels for actuating thevarious systems of the apparatus, the system requiring only one aircompressor and compressor motor.

While only one embodiment of the apparatus, together with modificationsthereof, has been described in detail herein and shown in theaccompanying drawing, it will be evident that various furthermodifications are possible in the arrangement and construction of itscomponents without departing from the scope of the invention.

What is claimed is:
 1. Apparatus for refrigerating containers of soft serve food products and for dispensing the soft serve products, each product container having an outlet, the apparatus comprising:a plurality of product container receptacles each adapted to receive a product container inserted therein respectively; refrigeration means, having respective cooling sections located adjacent each of the receptacles for cooling each of the receptacles and any product container contained therein; dispensing means, connectable in communication with product containers inserted within the receptacles, respectively, for dispensing a quantity of the product disposed in the product containers, respectively; and the refrigeration means further comprising means for conducting refrigerant to the respective cooling sections and for selectively controlling the temperature within each receptacle controlling refrigerant flow to the respective cooling sections adjacent each receptacle for controlling the temperatures of the food product in the product containers, respectively, appropriate for different food products in the respective product containers.
 2. The apparatus of claim 1, wherein the refrigeration means comprises means for compressing and condensing a refrigerant and for selectively conducting the condensed refrigerant to the respective cooling sections.
 3. The apparatus of claim 1, wherein the product containers comprise elongated impervious containers having heat sink structures contained therein, respectively, wherein the heat sink structure of each respective product container comprises an elongated structure extending within the respective product container, and wherein the cooling section comprises conduit means for circulating refrigerant adjacent the heat sink structure of a respective product container and for removing heat from the heat sink structure and the food product contained within the product container.
 4. The apparatus of claim 3, wherein the cooling sections adjacent the respective receptacles each comprise a conduit which extends peripherally around the receptacle.
 5. The apparatus of claim 1, further comprising adjustable thermostatic temperature control means for permitting independent control of the temperature maintained within each respective product container.
 6. Apparatus for refrigerating containers of soft serve food products and for dispensing the soft serve products, each product container comprising an elongated, impervious container having an outlet at one end, the apparatus comprising:a housing; a plurality of product container receptacles supported within the housing and adapted to receive respective product containers removably inserted therein; refrigeration means for cooling the product container receptacles and any product containers inserted therein; dispensing means, connectable with the outlets of the product containers, for dispensing a quantity of the food product contained within a selected one of the product containers, respectively, the dispensing means comprising a plurality of dispensing units operatively associated with the respective product container receptacles, each unit having a dispensing valve connectable with the outlet of a respective product container, and an actuator system operatively connected to the dispensing valve of each respective dispensing unit and comprising a piston operably connected to the dispensing valve and disposed in a chamber formed in an actuator housing, and means for causing pressure fluid to flow to said chamber to effect gradual opening of said dispensing valve to provide a gradually accelerating flow of food product from a respective product container.
 7. Apparatus for refrigerating a plurality of product containers of soft serve food product and for dispensing quantities of soft serve food product from a selected one of the product containers, the apparatus comprising:a housing; a plurality of product container receptacles mounted within the housing for receiving respective product containers; a refrigeration system having a compressor, a condenser, and a plurality of evaporator sections mounted within the housing adjacent respective ones of the product container receptacles; a plurality of refrigerant supply means, connected between the condenser and respective ones of the evaporator sections, for conducting condensed refrigerant to the respective evaporator sections; means for selectively controlling the refrigerant flow to the respective evaporator sections for controlling the temperatures of the food products in the respective product containers appropriate for different food products in the respective product containers; and product dispensing units removably mountable in communication with respective containers of soft serve product.
 8. The apparatus of claim 7, wherein the evaporator sections comprise respective conduits positioned adjacent the respective product container receptacles.
 9. The apparatus of claim 8, wherein the product container receptacles comprise elongated barrels for receiving the respective product containers and wherein the evaporator sections comprise respective cooling coils extending around the periphery of the respective product container barrels.
 10. The apparatus of claim 9, wherein the product containers are of a type having an open end having a heat sink structure provided therein and a closed end spaced from the heat sink structure, and wherein the evaporator sections are positioned adjacent and in alignment with the heat sink structures of respective product containers, upon the product containers being seated within the respective product container receptacles.
 11. The apparatus of claim 10, further comprising a defrosting system comprising means, connected with the outlet of the compressor and communicating with the evaporator sections, for conducting compressed, heated refrigerant in gaseous form through the evaporator sections, respectively.
 12. The apparatus of claim 7, further comprising means for supplying gas under a first pressure to the respective product containers for effecting extrusion of the soft serve product.
 13. Apparatus for refrigerating product containers of soft serve food products and for selectively dispensing quantities of the soft serve products, the product containers each comprising an elongated, impervious, flexible bag having an outlet at one end, the apparatus comprising:a housing; a plurality of chilled receptacle means for receiving respective product containers, each receptacle means having an outlet connectable in communication with the open end portion of a respective flexible product container contained therein and having a barrel section adapted for receiving the product container; refrigeration means for cooling the barrels of the receptacle means and any product containers therein; dispensing means for dispensing a selected product contained within a container inserted in one of the product container receptacles by compressing its flexible bag to cause the food product to flow outwardly through the outlet; a monitoring system, comprising means for detecting the exhaustion of substantially all of the food product contained within the respective product containers by monitoring the volume of a fluid exhausted from a space within the product receptacle means and external of the flexible bags, respectively.
 14. Apparatus for refrigerating containers of soft serve food products and for dispensing the soft serve food products, each container comprising an elongated, impervious product container having an outlet at one end, the apparatus comprising:a housing; a plurality of product container receptacles supported within the housing and adapted to receive respective product containers removably inserted therein; refrigeration means for cooling the product container receptacles and any product containers inserted therein; dispensing means, connectable with the outlets of the product containers, for dispensing a quantity of the food product contained within a selected one of the product containers, the dispensing means comprising a plurality of dispensing units operatively associated with the respective product container receptacles, each dispensing unit having a dispensing valve connectable with the outlet of a respective product container; an actuator system operatively connected to the dispensing valve of each respective dispensing unit and comprising an actuator having a piston member operatively connected to the respective dispensing valve, first and second piston chamber sections being defined on opposite sides of the piston member, the actuator system further comprising an accumulator containing a liquid medium and having communication with the first chamber section, and further comprising means for applying a gas under a first pressure within the accumulator for causing the liquid medium to flow from the accumulator to the first chamber section for translating the piston member toward the second chamber section and for opening the dispensing valve; and means for shutting off the flow of gas to the accumulator and for applying a gas under a second, lower pressure to the second chamber section for opposing movement of the piston member toward the second chamber section, and, upon pressure within the first chamber section being reduced, for translating the piston member toward the first chamber section and closing the dispensing valve.
 15. Apparatus for refrigerating containers of soft serve food products and for dispensing the soft serve food products, each container comprising an elongated, impervious product container having an outlet at one end, the apparatus comprising:a housing; a plurality of product container receptacles supported within the housing and adapted to receive respective product containers removably inserted therein; refrigeration means for cooling the product container receptacles and any product containers inserted therein; dispensing means, connectable with the outlets of the product containers, for dispensing a quantity of the food product contained within a selected one of the product containers, the dispensing means comprising a plurality of dispensing units operatively associated with the respective product container receptacles, each dispensing unit having a dispensing valve connectable with the outlet of a respective product container, further comprising an actuator system operatively connected to the dispensing valve of each respective dispensing unit; and means for supplying gas to the respective dispensing units under a first pressure and under a second pressure, comprising a single air compressor, a first reservoir adapted to receive gas under said first pressure, a second reservoir adapted to receive gas under a second pressure lower than said first pressure, and regulating and valving means connected between the compressor and the first and second reservoirs for supplying gas under said first pressure to the respective dispensing units and for supplying gas from the second reservoir under a third pressure, lower than said first and second pressures, to the dispensing units.
 16. Apparatus for refrigerating a plurality of product containers of soft serve food product and for dispensing quantities of soft serve food product from a selected one of the product containers, the apparatus comprising:a housing; a plurality of product container receptacles mounted within the housing for receiving respective product containers; product dispensing units removably mountable in communication with the respective product containers; a refrigeration system having a compressor, a condenser, and a plurality of evaporator sections mounted within the housing adjacent respective ones of the product container receptacles; a plurality of refrigerant supply means, connected between the condenser and respective ones of the evaporator sections, for conducting condensed refrigerant to the respective evaporator sections; means for selectively controlling the refrigerant flow to the respective evaporator sections; and a defrosting system comprising means, connected with the outlet of the compressor and communicating with the evaporator sections, for conducting compressed, heated refrigerant in gaseous form through the evaporator sections, said defrosting system comprising means for increasing the temperature of the product container receptacles for thawing ice deposits which may have formed between the product container receptacles and any product containers therein, respectively.
 17. Apparatus for refrigerating a plurality of product containers of soft serve food product and for dispensing quantities of soft serve food product from a selected one of the product containers, the apparatus comprising:a housing, a plurality of product container receptacles mounted within the housing for receiving respective product containers; product dispensing units removably mountable in communication with respective product containers of soft serve food product; a refrigeration system having a compressor, a condenser, and a plurality of evaporator sections mounted within the housing adjacent respective ones of the product container receptacles; a plurality of refrigerant supply means, connected between the condenser and respective ones of the evaporator sections, for conducting condensed refrigerant to the respective evaporator sections; means for selectively controlling the refrigerant flow to the respective evaporator sections; and a defrosting system comprising means, connected with the outlet of the compressor and communicating with the evaporator sections, for conducting compressed, heated refrigerant in gaseous form through the evaporator sections, said defrosting system including a manifold and conduits connected to the manifold for supplying refrigerant to the respective evaporator sections and valving means for permitting flow of refrigerant to the evaporator sections from the compressor and preventing any reverse flow of refrigerant to the manifold.
 18. Apparatus for refrigerating product containers of soft serve food products and for selectively dispensing quantities of the soft serve food products, the product containers each comprising an elongated, impervious, flexible bag having an outlet at one end, the apparatus comprising:a housing; a plurality of chilled receptacle means for receiving respective product containers, each receptacle means having an outlet connectable in communication with an open end portion of a respective product container contained therein and having a barrel section adapted for receiving the product container; refrigeration means for cooling the barrel sections of the receptacles means, respectively, and any food product therein; dispensing means for dispensing a selected product contained within a product container inserted in one of the receptacle means by compressing its flexible bag to cause the food product to flow outwardly through the outlet; and a monitoring system, comprising means for detecting the exhaustion of substantially all of the food product contained within the respective product containers, the monitoring system including means operable for monitoring the volume within the receptacle means and external of the flexible bags, respectively, the monitoring system further comprising means for introducing a gas within each receptacle means and within a respective product container inserted therein, external of the flexible bag of the respective product container, and for determining the volume of the residual space within the product container relative to a predetermined volume corresponding to a product empty condition, by comparing the volume of gas within the residual space with that associated with a product empty condition.
 19. The apparatus of claim 18, wherein the gas introduced within the residual space within a respective one of the receptacle means is exhausted through a restrictive orifice and wherein the time required for the gas to fall from a first pressure to a second pressure is compared with a predetermined value corresponding to a condition in which the food product within the respective product container has been substantially exhausted. 